One of the most potent indoor allergens is house dust contaminated with dust mites. It is thought that dust mites may be an important factor in between 50 to 80 percent of all asthma cases, and contributes to countless cases of eczema, hay fever and other allergic reactions. Symptoms of hypersensitivity to dust mites include sneezing, itching, watery eyes, as well as headaches, fatigue and depression. Respiratory ailments associated with dust mites result from contact with proteins in the digestive juices from the dust mite gut which are carried on the fecal pellets, and exposure to dust mites in the first, critical year of life can trigger a lifelong allergy. There is no known cure for dust mite allergies, only prevention through the control of dust mite levels.
Beds are the primary habitat for dust mites. A typical mattress may harbor anywhere from 100,000 to 10 million mites. Nearly ten percent of a well-used pillow is composed of dead mites and their droppings. Mites prefer warm, moist surroundings such as the top surfaces of a mattress while the human occupant is asleep, and their major source of food is the dead skin shed from humans and their pets. Significant numbers of mites can also be found in bedroom carpeting and household upholstery.
Currently, at least two products are commercially available for control of dust mites. They contain benzyl benzoate and/or tannic acid as active ingredients. Benzoic acid esters, such as benzyl benzoate, are effective agents for killing house dust mites based on laboratory testing and field evaluations. Benzyl benzoate does not pose a serious health risk when used in the amounts needed to kill mites because it is rapidly metabolized to hippuric acid, which is excreted in urine.
Although benzyl benzoate is an effective miticide, its use is not without problems. For cost and safety reasons, benzyl benzoate is diluted when used to control dust mites. However, benzyl benzoate is insoluble in water, and is therefore ineffective as an aqueous spray. In commercial miticides, benzyl benzoate is adsorbed on solid particles to aid in its dispersion. The resulting dispersion is applied as either a moist powder or foam to carpets and bedding. One drawback is that the moist powder tends to clump together, so that it is difficult to apply evenly. Another drawback is that solid-stabilized benzyl benzoate miticides leave behind a powdery residue that is easily removed by vacuuming, which reduces its effectiveness.
The present invention is directed to overcoming, or at least minimizing, one or more of the problems set forth above.